How much is too much? Well I hate spending too much time on a computer processing images. That's why I shoot in RAW format as the amount of detail is often hidden and you can change this by just adjusting the brightness and contrast.
This image was shot in Cameos Garden, a famous place in Macau where Bruce Lee had a scene at the entrance of the park featured in the movie, Fist of Fury.

@Tapsamai, @takashi02 The first difference is the price! It cost a bomb to own Photoshop so you know that it does more. But Photoshop is more for graphic designers as it is basically a graphical tool and not a photographers' tool. Photoshop lets you do stuff like adding layers to an image as well as text. Lightroom on the other hand is more like Color EFex Pro 4, it lets you edit the photos and apply filters. Photographers who have no need to manipulate images but improve their look will appreciate Lightroom and Color eFex Pro. For me, one piece of software is enough so I stuck with Lightroom. I did use Aperture from the beginning but found the two to be too similar in function so I gave one of them up. Nik Software's Color Efex Pro is priced in the same ballpark as Lightroom and Aperture so you know that they do similar stuff.